Cook the chana dal in a pressure cooker till 2 whistles and set aside. Wash, peel and chop the cucumber into small pieces and keep them aside. Heat oil in a cooking vessel and add the mustard seeds, chana dal and urad dal and let them splutter. Now add the green chillies, red chilli and curry leaves to it and fry for a few seconds. Then add the chopped cucumber, salt, turmeric and little water and mix well. Cover with a lid and let it cook completely. Now add the cooked chana dal and grated coconut and mix well. Fry for 2 minutes and turn off the heat. Serve hot with rice or roti.